Teeli® permanent filters are made from highest quality German stainless steel mesh guaranteeing true-flavor filtering. They are extremely durable, lasting decades and may be used for all teas and infusions, with out flavor transferring. They are dishwasher safe and most importantly, the best way to enjoy your tea! Loose leaf tea brewed in these filters is the healthful and most planet conscious way of enjoying tea. No worrying about bleaching or plastic-paper woven non-biodegrading bags. Please compost your spent leaves or turn out into the garden. I use the medium filters color-coordinated to my extensive pottery and china collection of teapots, cups and mugs. The large size is my preferred way to make iced teas and concentrates/syrups. They fit perfectly into my Italian Frigoverre airtight jugs and my larger teapots. I keep dozens of these filters in my kitchen!